Ketoprofen–cysteine equimolar salt

Abstract

Pharmaceutical salts had been defined as “compounds” formed between a molecular or ionic active pharmaceutical substance and a salt former. Like cocrystals, salts are mainly prepared in order to increase the biodisponibility of the active substance. In this paper, we present the formation of a pharmaceutical salt prepared by cocrystallization which was obtained from ketoprofen (KT) and cysteine (Cys). The physicochemical properties of the KT–Cys salt were investigated by thermal analysis, Fourier-transform infrared spectroscopy and powder X-ray diffraction (PXRD) techniques. The heat flow curve of the KT–Cys is different from the ones of KT and Cys and suggests that under experimental conditions, the interaction between the two compounds occurred. This aspect and the corroboration with the results from spectroscopy and PXRD data confirmed the formation of a salt and the absence of any unbound component.